JP4442341B2 - Seat belt tension detector - Google Patents

Description

  The present invention relates to a seat belt tension detection device that is installed in an anchor portion that fixes a seat belt to a vehicle and detects a tension applied to the seat belt.

  As a conventional example of a device for detecting the tension of the seat belt, a leaf spring on which the tension of the seat belt acts is provided at a seat belt attachment portion of the seat belt tension detecting device, and a strain gauge is attached to the leaf spring. Therefore, the tension of the seat belt is detected from the distortion of the leaf spring that deforms according to the tension of the seat belt.

As prior art document information related to the invention of this application, for example, Patent Document 1 and Patent Document 2 are known.
US Pat. No. 5,996,421 JP 2001-354114 A

  There is a need for a seat belt tension detection device that is smaller, lower in cost, superior in performance or durability, and equipped with a failure diagnosis function. However, the above-described conventional configuration uses the lever lever lever principle. Therefore, there is a problem that the height is necessary, and it is difficult to reduce the height and the size.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a seat belt tension detecting device that is small in size, low in cost, excellent in tension detection accuracy or durability, and capable of performing failure diagnosis of the detecting device.

  In order to achieve the above object, the present invention has the following configuration.

According to a first aspect of the present invention, there is provided an anchor connecting member having a connecting portion to a vehicle structure, a seat belt connecting member having a connecting portion to a seat belt, and an elastic connection between the two members. And an elastic coupling mechanism that transmits a tension applied to the seat belt, a sensor pressing portion that transmits a force applied to the elastic coupling mechanism, and the anchor coupling member that detects a force applied to the sensor pressing portion. A strain sensor, a strain output processing circuit, and a cover that covers the anchor connecting member are provided, and the seat belt connecting member, the elastic connecting mechanism, the sensor pressing portion, and the strain sensor are arranged on the same straight line, so that the height is reduced. Therefore, since the influence of friction between the members is small, the effect of detecting the tension of the seat belt with higher accuracy can be obtained. Also, by providing semi-cylindrical protrusions in the thickness direction of the four corners of the seat belt connecting member, for example, when the seat belt connecting member is viewed from above the seat belt tension detecting device, the displacement with respect to the left and right rotational directions is shifted. Therefore, the tension applied to the seat belt can be transmitted to the strain sensor without losing the seat belt with certainty, so that the effect of detecting the tension of the seat belt with high accuracy can be obtained.

According to a second aspect of the present invention, there is provided an anchor connecting member having a connecting portion to a vehicle structure, a seat belt connecting member having a connecting portion to a seat belt, and an elastic connection between the two members. And an elastic coupling mechanism that transmits a tension applied to the seat belt, a sensor pressing portion that transmits a force applied to the elastic coupling mechanism, and the anchor coupling member that detects a force applied to the sensor pressing portion. A strain sensor, a strain output processing circuit, and a cover that covers the anchor connecting member are provided, and the seat belt connecting member, the elastic connecting mechanism, the sensor pressing portion, and the strain sensor are arranged on the same straight line, so that the height is reduced. Therefore, since the influence of friction between the members is small, the effect of detecting the tension of the seat belt with higher accuracy can be obtained. Also, by providing at least two or more semi-cylindrical protrusions on the upper and lower surfaces inside the cover in the cover longitudinal direction, it is possible to prevent displacement with respect to the left and right rotational directions and to reliably lose the tension applied to the seat belt. Therefore, it can be transmitted to the strain sensor without any problem, so that the effect of detecting the tension of the seat belt with high accuracy can be obtained.

In the invention according to claim 3 of the present invention, in particular, the elastic coupling mechanism is constituted by a compression coil spring, and the tension force can be controlled with high accuracy by utilizing the spring characteristics, and the seat belt can be controlled with higher accuracy. The effect that the tension | tensile_strength of this can be detected is acquired.

The invention according to claim 4 of the present invention is configured such that the effective detection area of the strain sensor is restricted by a stopper provided on the slide convex portion of the anchor connecting member. For example, a large force outside the specified range is applied. Even if it is added to the strain sensor, it is possible to limit the detection range of the strain sensor by providing the stopper, so that the durability of the strain sensor can be improved. In addition, since the effective detection area of the strain sensor is regulated by the stopper, indicating the output of the area outside the detection range can be determined that some abnormality has occurred in the detection apparatus. The effect that it can be performed is obtained.

According to the fifth aspect of the present invention, the strain sensor is formed in a flat plate shape, and a part of the strain sensor can be locally distorted and deformed by providing an acute angle portion at a part thereof. Since it can be taken large without variation, it is possible to obtain an operational effect that tension can be detected with high accuracy.

In the invention according to claim 6 of the present invention, the center of the flat plate-shaped strain sensor is fixed, and the tension applied to the seat belt is horizontally applied to both ends of the strain sensor. Since the tension and compression portions can be provided on the same surface, the effect of being able to easily obtain the output of the strain sensor with high resolution is obtained.

  In the invention according to claim 7 of the present invention, the portion where the seat belt of the seat belt connecting member is fixed is curved to prevent the tension from being dispersed, and the tension is applied to the center of the curved portion. Since it can be concentrated, the effect that the seat belt tension can be detected with high accuracy is obtained.

  According to the present invention, it is possible to provide a seatbelt tension detecting device that can be reduced in height and increased in accuracy, and further has an advantage that a failure diagnosis of the detecting device can be performed.

  FIG. 1 is a perspective view showing an overall configuration of a seat belt tension detecting device (seat belt tension sensor) according to an embodiment of the present invention.

  In FIG. 1, the seat belt tension detecting device 1 is configured so that the sensor pressing portion 6 applies a seat belt tension to both ends of the strain sensor 10 on the anchor connecting member 3 integrally formed with the strain sensor 10 and the strain output processing circuit 11. The elastic coupling mechanism 5 is inserted after the strain sensor is inserted. The elastic coupling mechanism 5 is a compression coil spring. Then, the seat belt connecting member 4 is inserted into the anchor connecting member 3 through the elastic connecting mechanism 5 so that the seat belt connecting member 4, the elastic connecting mechanism 5, the sensor pressing portion 6, and the strain sensor 10 are on the same straight line. Has been placed. Further, the cover 7 is provided with square holes on the upper and lower surfaces so that the seat belt 2 is attached in contact with the seat belt connecting member 4 so as to cover the seat belt tension detecting device 1, and the cover lid 8 covers the anchor connecting member 3 of the cover 7. The insertion portion surface is covered and integrated with the cover 7.

  The seat belt tension detecting device 1 configured as described above is fixed to the vehicle body and bolts through the screw holes 13 of the anchor connecting member 3. When the seat belt 2 is pulled in this state, the seat belt connecting member 4 is applied to the sensor pressing portion 6 via the elastic connecting mechanism 5 while sliding the anchor connecting member 3 by the tension, and finally the strain sensor 10 is applied. The force is transmitted.

  Hereinafter, details of each part of the seat belt tension detection device 1 will be described.

  FIG. 2 is a view showing the anchor connecting member 3 of the seat belt tension detecting apparatus 1 according to the embodiment of the present invention. FIG. 2A is a plan view thereof, and FIG. 2B is a sectional view thereof. As shown in FIG. 2A, the anchor connecting member 3 is obtained by pressing a flat stainless steel material. By this pressing, the strain sensor 10, the slide convex portions 12a and 12b, the stoppers 14a and 14b, and the screw holes 13 are obtained. Is formed. The strain sensor 10 is subjected to several printing processes and firing processes on a plane, and strain resistors are formed. At the same time, signals from these strain resistors are amplified to finally reduce the strain amount. A distortion output processing circuit 11 for processing so as to be detected is formed. By this step, the strain sensor 10 and the strain output processing circuit 11 can be integrally formed on the anchor connecting member 3, which is advantageous in reducing the height and cost. Further, the stoppers 14a and 14b of the anchor connecting member 3 are respectively provided on a part of the upper surfaces of the slide convex portions 12a and 12b, and the stoppers 14a and 14b are convex upward as shown in FIG. Thus, when the seat belt connecting member 4 slides on the slide convex portions 12a and 12b, the seat belt connecting member 4 is blocked by the stoppers 14a and 14b. This is because the strain sensor 10 is destroyed by the tension transmitted from the sensor pressing portion 6 via the seat belt connecting member 4 and the elastic connecting mechanism 5 when a particularly excessive tension is applied to the seat belt 2 at the time of a vehicle collision. Therefore, the stoppers 14a and 14b are arranged so as to restrict the effective detection area of the strain sensor 10. With such a configuration, the durability of the strain sensor 10 can be improved. In addition, since the effective detection area of the strain sensor 10 is restricted by the stoppers 14a and 14b, indicating the output of the area outside the detection range can be determined that some abnormality has occurred in the detection device, and failure diagnosis can be performed. The effect that it can be performed is obtained.

  FIG. 3 is an explanatory diagram of the strain sensor 10 when the seat belt is in tension. For example, when the seat belt 2 is pulled with a tension W in FIG. 1, the seat belt tension W is applied from the seat belt connecting member 4 to the strain sensor 10 from the sensor pressing portion 6 through the elastic connecting mechanism 5. If this is shown in detail in FIG. 3, W / 2 seat belt tension is applied to both ends of the strain sensor 10. At this time, a tensile stress is applied to the hatched portion on the same plane, and strain resistors Ra and Rc are formed there. On the other hand, compressive stress is applied to the portion of the vertical stripe line, and strain resistors Rb and Rd are formed there. In general, the resistance value of a strain resistor increases during tensile stress, and conversely decreases when compressive stress is applied. Further, by providing the strain sensor 10 with the acute angle portions 15a, 15b, 15c and 15d, stress can be concentrated around the respective acute angle portions 15a, 15b, 15c and 15d. Variations in resistance value due to stress of the bodies Ra, Rb, Rc, and Rd can be reduced. Accordingly, at this time, the resistance values of the strain resistors Ra and Rc increase, and conversely, the resistance values of the strain resistors Rb and Rd decrease. Therefore, these are the strain output processing circuit 11 having the circuit configuration shown in FIG. In this way, it is possible to obtain a highly sensitive output efficiently and to detect the tension of the seat belt with a small variation and a high accuracy.

  FIG. 5 is a view showing the seat belt connecting member 4 of the seat belt tension detecting device 1. 5A is a perspective view thereof, and FIG. 5B is a sectional view thereof. In FIG. 5A, the seat belt pressing portion 22 has a curved shape, and when the seat belt 2 is pulled, the seat belt gathers in the central direction of the curved portion of the seat belt pressing portion 22, and the tension is the seat. It concentrates on the center of the curved part of the belt pressing part 22. Therefore, variation when the seat belt tension is transmitted to the strain sensor 10 is reduced, and high-precision strain detection is possible. The slide recesses 24 a and 24 b on the side surfaces of the seat belt connecting member 4 slide on the slide convex portions 12 a and 12 b of the anchor connecting member 3. At this time, the projections 21a, 21b, 21c, and 21d provided at the corners of the four corners of the seat belt connecting member 4 have a semi-cylindrical shape in the thickness direction, and the surface thereof is slippery. These are in contact with the inner side surfaces of the square holes in the anchor connecting member 3. As a result, when the seat belt connecting member 4 slides the anchor connecting member 3, it does not rotate left and right in the traveling direction and is hardly affected by friction, so that the seat belt tension is not reliably lost. Since it can be transmitted to the strain sensor 10, it is possible to detect the seat belt tension with high accuracy.

  FIG. 5B is a longitudinal sectional view of the seat belt connecting member 4. The insertion hole 23 is a two-stage hole. When the compression coil spring as the elastic coupling mechanism 5 and the shaft 41 of the sensor pressing portion 6 shown in FIG. 8 are inserted, the compression coil spring of the elastic coupling mechanism 5 is compressed. 41 extends within the tension detection range to the smaller hole provided in two stages. The tension of the strain sensor 10 applied from the sensor pressing unit 6 is controlled by the characteristics of the elastic coupling mechanism 5 formed of a compression coil spring. When the tension detection range is exceeded, there is a wall at the tip of the smaller hole provided in two stages, so that the shaft 41 is blocked by the wall so that it cannot extend further. It is configured to protect. Moreover, since it can be determined that some abnormality has occurred in the detection device, indicating the output of the region outside the detection range by this means that it is possible to obtain an operational effect that a failure diagnosis of the detection device can be performed. .

  FIG. 6 is a plan view showing the elastic coupling mechanism 5 composed of a compression coil spring of the seat belt tension detecting device 1. The specifications of the elastic coupling mechanism 5 composed of this compression coil spring are, for example, material SWP-A, wire diameter 1.5 mm, spring outer diameter 9.5 mm, spring length 15 mm, effective number of turns 5, spring constant 20 N / mm, initial tension 0 N The spring pitch is 3 mm, and the compression coil spring expands and contracts in the range of about 6 mm, resulting in the characteristics shown in FIG. As shown in FIG. 1, the elastic coupling mechanism 5 including the compression coil spring couples the seat belt coupling member 4 and the sensor pressing portion 6 and finally transmits the seat belt tension to the strain sensor 10. It is compressed according to the characteristics of the compression coil spring. Therefore, as shown in FIG. 7, the compression coil spring can transmit the seat belt tension to the strain sensor 10 in proportion to the compression length of the spring, but the compression length of the spring is 6 mm. If exceeded, the strain sensor 10 is not applied with a tension exceeding 120 N or more at the maximum, so that the durability of the strain sensor 10 can be improved. In addition, since it can be determined that some abnormality has occurred in the detection device, showing the output of the region outside the detection range can provide an operational effect that a failure diagnosis of the detection device can be performed.

  FIG. 8 is a perspective view showing the sensor pressing portion 6 of the seat belt tension detecting device 1. The sensor pressing portion 6 is made by, for example, die casting, and the material is iron or stainless steel. The U-shaped bearing 43 and the shaft 41 are integrated, and the bearing 43 is provided with sandwiched portions 42a and 42b. It has become. Since the sandwiching portions 42a and 42b are concave so as to sandwich both ends of the strain sensor 10 and the tip of the recess is circular, when the strain sensor 10 is sandwiched, the contact between the strain sensor 10 and the sandwiching portions 42a and 42b. The parts are not affected by friction. Further, when the seat belt tension is applied to the strain sensor 10, the strain sensor 10 is sandwiched so that the strain sensor 10 can be transmitted horizontally without error without being rotated or twisted. Can be detected.

  FIG. 9 is a perspective view of the cover 7 that covers the seat belt tension detector 1. The cover 7 is formed, for example, by resin molding such as ABS. First, square holes 51 a and 51 b for passing the seat belt 2 are provided on the upper and lower surfaces, and the outer periphery of the anchor connecting member 3 is slid inside the cover 7. Slide portions 52a and 52b for fixing the seat belt, and semicircular projections 53a, 53b, 53c, and 53d are provided to suppress the rotation of the seat belt connecting member 4, and the projection of the cover lid 8 is further provided. Insertion holes 54a and 54b for fixing 63a and 63b are provided vertically. More specifically, the slide portions 52a and 52b are arranged such that the recesses are disposed from end to end in the longitudinal direction of the cover 7, and are fixed so that the outer periphery of the anchor connecting member 3 is sandwiched. Further, the protrusions 53a, 53b, 53c, 53d have a semi-cylindrical shape and are arranged from end to end in the longitudinal direction of the cover 7 except for the square holes 51a, 51b, and the seat belt connecting member 4 is anchor-connected. When the member 3 is slid, the protrusions 53a, 53b, 53c, and 53d come into contact with the upper and lower surfaces of the seat belt connecting member 4 so as to prevent the seat belt connecting member 4 from rotating or moving up and down. Thus, the seat belt tension is transmitted to the strain sensor 10 without any loss, so that it is possible to detect the seat belt tension with high accuracy.

  FIG. 10 is a perspective view showing the cover lid 8 of the seat belt tension detecting device 1. The cover lid 8 is formed by resin molding such as ABS like the cover 7, and is provided with stoppers 61a and 61b, holes 62 and projections 63a and 63b. The stoppers 61a and 61b are provided to prevent the seat belt connecting member 4 from being displaced in the direction opposite to the tension direction of the seat belt 2 due to the reaction force of the elastic connecting mechanism 5. For example, as shown in FIG. When the tension is released from the state in which the seat belt 2 is pulled and the compression coil spring of the elastic coupling mechanism 5 is compressed, the seat belt coupling member 4 moves in the direction opposite to the tension direction of the seat belt due to the reaction force of the compression coil spring. This is to prevent the detachment from the anchor connecting member 3 in advance. The hole 62 is for passing the anchor connecting member 3, and the protrusions 63 a and 63 b are inserted and fixed in the holes 54 a and 54 b of the cover 7 so as to be integrated with the cover 7.

  The seat belt tension detection device according to the present invention can be reduced in height and accuracy, and can provide a seat belt tension detection device capable of performing failure diagnosis of the detection device. It is useful for a seat belt tension detecting device for a vehicle that is installed on a fixed anchor portion and detects a tension applied to a belt.

The perspective view which shows the whole structure of the seatbelt tension detection apparatus in embodiment of this invention. (A) The front view which shows the anchor connection member of the seatbelt tension detection apparatus, (B) The sectional view Explanatory drawing of the strain sensor of the seat belt tension detector at the time of seat belt tension Schematic showing the circuit configuration of the strain output processing circuit of the seat belt tension detector (A) The perspective view for demonstrating the seatbelt connection member of the seatbelt tension detection apparatus, (B) The sectional view The top view which shows the elastic connection mechanism which consists of a compression coil spring of the seatbelt tension detection apparatus The figure which shows the characteristic of the elastic connection mechanism which consists of a compression coil spring of the seatbelt tension detection apparatus The perspective view which shows the sensor press part of the same seatbelt tension detection apparatus The perspective view which shows the cover of the same seatbelt tension detection apparatus The perspective view which shows the cover cover of the same seatbelt tension detection apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seat belt tension | tensile_strength detection apparatus 2 Seat belt 3 Anchor connection member 4 Seat belt connection member 5 Elastic connection mechanism 6 Sensor press part 7 Cover 8 Cover lid 10 Strain sensor 11 Strain output processing circuit 12a, 12b Slide convex part 13 Screw hole 14a, 14b Stopper 15a, 15b, 15c, 15d Acute angle part 21a, 21b, 21c, 21d Protrusion part 22 Seat belt pressing part 23 Insertion hole 24a, 24b Slide concave part 41 Shaft 42a, 42b Clamping part 43 Bearing 51a, 51b Square hole 52a, 52b Slide 53a, 53b, 53c, 53d Protrusion 54a, 54b Insertion hole 61a, 61b Stopper 62 Hole 63a, 63b Protrusion

Claims (7)

An anchor connecting member having a connecting portion to a vehicle structure, a seat belt connecting member having a connecting portion to a seat belt, and an elastic connecting for elastically connecting the two members to transmit tension applied to the seat belt. A mechanism, a sensor pressing part for transmitting a force applied to the elastic connecting mechanism, a strain sensor and a strain output processing circuit provided integrally with the anchor connecting member for detecting a force applied to the sensor pressing part, and the anchor connection A cover for covering the member is provided, and the seat belt connecting member, the elastic connecting mechanism, the sensor pressing portion, and the strain sensor are arranged on the same straight line, and a semi-cylindrical protrusion is formed in the thickness direction of the four corners of the seat belt connecting member. the seat belt tension sensing device. An anchor connecting member having a connecting portion to a vehicle structure, a seat belt connecting member having a connecting portion to a seat belt, and an elastic connecting for elastically connecting the two members to transmit tension applied to the seat belt. A mechanism, a sensor pressing part for transmitting a force applied to the elastic connecting mechanism, a strain sensor and a strain output processing circuit provided integrally with the anchor connecting member for detecting a force applied to the sensor pressing part, and the anchor connection A cover for covering the member; and the seat belt connecting member, the elastic connecting mechanism, the sensor pressing portion, and the strain sensor are arranged on the same straight line, and at least two or more semi-cylindrical protrusions are formed on the upper and lower surfaces inside the cover. Seat belt tension detection device provided in the longitudinal direction of the cover . The seat belt tension detecting device according to claim 1 or 2 , wherein the elastic coupling mechanism is constituted by a compression coil spring. The seat belt tension detecting device according to claim 1 or 2 , wherein an effective detection area of the strain sensor is restricted by a stopper provided on the anchor connecting member. The seatbelt tension detecting device according to claim 1 or 2 , wherein the strain sensor is formed in a flat plate shape, and an acute angle portion is provided in a part thereof. 6. The seat belt tension detecting device according to claim 5 , wherein the center of the flat plate-shaped strain sensor is fixed, and the tension applied to the seat belt is horizontally applied to both ends thereof. The seat belt tension detecting device according to claim 1 , wherein a portion of the seat belt connecting member to which the seat belt is fixed is curved.

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